1. Field of the Invention
Apparatuses and methods consistent with the present invention relate to bias current control, and more particularly, to a radio frequency (RF) signal receiver for controlling a bias current and a method for controlling a bias current, in which a bias current of each of a plurality of modules of an analog signal processing module is controlled by counting error bits sensed by a demodulator.
2. Description of the Related Art
With the recent development of semiconductor and communication technologies, mobile products have come into wide use.
The general configuration of such a mobile product is shown in FIGS. 1 and 2.
FIG. 1 is a block diagram of a conventional radio frequency (RF) signal receiver.
Referring to FIG. 1, the RF, signal receiver includes an antenna 110, an analog signal processing module 130, and a digital signal processing module 150. The analog signal processing module 130 includes a bandpass filter 131, a low-noise amplifier 133, a mixer 135, an intermediate frequency (IF) amplifier, and a channel filter 139. The digital signal processing module 150 includes an analog/digital (A/D) converter 151, a demodulator 153, and a decoder 155.
An RF signal received through the antenna 110 is input to the bandpass filter 131. The bandpass filter 131 filters the RF signal to obtain a frequency band including at least one channel. The low-noise amplifier 133 amplifies a signal in a specific frequency band, for example, a broadcasting frequency band of 54-860 MHz, and suppresses noise. The gain of the low-noise amplifier 133 can be adjusted automatically.
The mixer 135 converts a signal output from the low-noise amplifier 133 to an IF signal and the IF amplifier 137 amplifies the IF signal. The channel filter 139 passes only a desired channel in the IF signal amplified by the IF amplifier 137 according to an analog signal processing method. A surface acoustic wave (SAW) filter may be used as the channel filter 139.
A channel signal selected by the channel filter 139 is input to the A/D converter 151 of the digital signal processing module 150, converted into a digital signal, and then demodulated into the original signal by the demodulator 153. The demodulator 153 checks if the demodulated signal is the same as the original signal and corrects an error to restore the original signal.
The decoder 155 decodes the signal demodulated by the demodulator 153 into an audio signal, a video signal, and a data signal and outputs them through a display screen or a speaker (not shown).
FIG. 2 is a block diagram of another conventional RF signal receiver.
Referring to FIG. 2, the RF signal processor includes an antenna 210, an analog signal processing module 230, and a digital signal processing module 250. The analog signal processing module 230 includes a bandpass filter 231, a low-noise amplifier 233, a mixer 235, an IF amplifier 237, a channel digital filter 239, and a digital-to-analog (D/A) converter 241. The digital signal processing module 250 includes an A/D converter 251, a demodulator 253, and a decoder 255.
An RF signal received through the antenna 210 is input to the bandpass filter 231. The bandpass filter 231 filters the RF signal to obtain a frequency band including at least one channel.
The low-noise amplifier 233 amplifies a signal in a specific frequency band, for example, a broadcasting frequency band of 54-860 MHz, and suppresses noise. The gain of the low-noise amplifier 233 may be adjusted automatically.
The mixer 235 converts a signal output from the low-noise amplifier 233 into an IF signal and the IF amplifier 237 amplifies the IF signal. The channel digital filter 239 passes only a desired channel in the IF signal amplified by the IF amplifier 237 according to a digital signal processing method, unlike the channel filter 139 of FIG. 1. To this end, the channel digital filter 239 may include an A/D converter for converting an analog signal amplified by the IF amplifier 237 into a digital signal.
A channel signal selected by the channel filter 239 is input to the D/A converter 241 and converted into an analog signal.
The analog signal is input to the A/D converter 251 of the digital signal processing module 250, converted into a digital signal, and then demodulated into the original signal by the demodulator 253. The demodulator 253 checks if the demodulated signal is the same as the original signal and corrects an error to restore the original signal.
The decoder 255 decodes the signal demodulated by the demodulator 253 into an audio signal, a video signal, and a data signal and outputs them through a display screen or a speaker (not shown).
Since a mobile product such as an RF signal receiver has ‘mobility’, its practicability is determined by not only the quality of a received signal but also compactness and a low-power feature, unlike in a wired environment.
Each of the RF signal receivers shown in FIGS. 1 and 2 has at least two chips, i.e., the analog signal processing module 130 (230) and the digital signal processing module 150 (250), resulting in a limitation in miniaturization. In particular, when an SAW filter is used as the channel filter 139 in FIG. 1, it has a larger volume than other RF components and thus hinders miniaturization, although the SAW, filter provides high performance. Moreover, in FIG. 2, the channel digital filter 239 may contribute to miniaturization by implementing an SAW filter through digital signal processing, but the D/A converter 241 should be added, resulting in a limitation in miniaturization.
The same bias current is supplied to various RF components included in the analog signal processing module 130 (230) regardless of the quality of a received signal, thus preventing efficient power control.
Therefore, it is necessary to efficiently manage power by miniaturizing an RF signal processor and controlling a bias current according to a receiving environment.